Offshore structures, such as floating production and drilling platforms are generally held in place using mooring or anchor chains attached to the floating structure by fixed chain stoppers. The chain stoppers are typically mounted on the deck of the floating structure with a bending shoe at the outboard edge of the deck. In some installations, the anchor chain is then guided down the side of the floating structure to a chain fairlead attached to the structure at or below the surface of the water.
The anchor or mooring chains are deflected below the water surface for two reasons. First, the mooring loads provide better stability and are more easily distributed over the floating structure, the lower the chains are attached to the structure. Secondly, there is less chance of other vessels colliding or hitting the mooring chains, the lower the mooring chains are positioned in the water.
A disadvantage in utilizing a chain fairlead is that the mooring chain must be deflected around the fairlead under extremely high mooring loads that are produced during operation of the floating offshore structure. This leads to premature chain wear and also excessive stress in the chain links.
Accordingly, there still remains a need for an improved chain stopper and fairlead device for mooring offshore platforms.